Microwave does not heat and shows E03 on the display.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Critical safety warning: High-voltage components inside a microwave (transformer, capacitor, magnetron) can store and generate lethal voltages. Do not open the cabinet or attempt to service these parts yourself.
- Basic checks only: Unplug the microwave. Inspect the power cord and outlet for damage or overheating. Try a different outlet on a dedicated circuit if possible.
- Rule out user settings: Ensure you are not in a low-power or demo mode. Reset the unit by unplugging for 5 minutes, then restoring power and reprogramming the clock.
- Test heating: Place a microwave-safe cup of water inside and run on full power for 1–2 minutes. If E03 appears and the water remains cold, the high-voltage system is likely faulty.
Next step: Because this error involves the high-voltage section, further diagnosis (magnetron, HV transformer, diode, capacitor) must be done by a Bosch-qualified technician with proper tools and training.